Study confirms DecisionDx-Melanoma accurately predicts metastatic risk in Stage I or Stage II patients who have no sign of disease beyond original tumor

Boston, MA—July 28, 2016—Castle Biosciences, Inc., a provider of molecular diagnostics to improve cancer treatment decisions, today announced the results from a study evaluating the performance of its gene expression profile (GEP) test DecisionDx®-Melanoma in a cohort of 356 Stage I and II melanoma patients. The data confirm findings from two previously published multicenter clinical validation studies and further support the test’s a bility to identify patients’ risk of melanoma recurrence in the five years following diagnosis. Results from the study, led by Dr. Laura Ferris, M.D., Ph.D., Associate Professor of Dermatology at the University of Pittsburgh, are being presented in a poster at the 2016 American Academy of Dermatology (AAD) Summer Meeting, and will be reviewed in a poster presentation on Saturday, July 30th at 10:20a.m. EDT.

“The majority of cutaneous melanoma patients who die from their disease each year are initially diagnosed as ‘low risk’ Stage I or II, highlighting the limitations of current staging methods,” said University of Pittsburgh’s Dr. Ferris, lead study author. “Improved methods for identifying cases of early stage, high risk melanoma, such as DecisionDx-Melanoma, could have a marked impact on patient care. For instance, the ability to more accurately identify risk in this population could lead to more appropriate surveillance plans that detect metastatic disease sooner, when the tumor burden is lower and the chance of responding to treatment is greatest.”

Multicenter Performance Study
In a study titled “Performance of a Prognostic 31-Gene Expression Profile test to Identify High Risk Stage I and II Melanoma Patients” (Abstract # 4067), 356 Stage I and II cutaneous melanoma tumors from 12 centers in the U.S. were analyzed in a CAP/CLIA-accredited laboratory using the DecisionDx-Melanoma test and classified as either low risk Class 1 or high risk Class 2. Study endpoints included recurrence-free survival (RFS), defined as time to either a regional or distant metastatic event, distant metastasis-free survival (DMFS), defined as time to any metastatic event beyond the regional node, and metastasis-free survival (MSS), defined as time from diagnosis to death documented as specifically resulting from melanoma. Topline results are below:

GEP test identified 71% of early stage melanoma tumors that recurred, 70% of those that metastasized distantly, and 80% of those that died from melanoma;

Using Cox multivariate analysis, GEP test was shown to be a significant predictor of both recurrence (p<0.002) and distant metastasis (p<0.04);

Low risk Class 1 patients in the cohort had negative predictive values for RFS, DMFS, and MSS of 90%, 93% and 99%, respectively;

Class 2 Stage I and II patients experienced rapid time to recurrence and distant metastasis (1.6 years median for both)

“This study, along with previously published data, demonstrates that the DecisionDx-Melanoma test can be used to identify high risk patients that may have been staged as low risk by the current staging system,” commented Derek Maetzold, President and CEO of Castle Biosciences. “These results, and the high negative predictive value rates for melanoma-specific survival observed in earlier DecisionDx-Melanoma studies, provide physicians an added level of confidence when developing patients’ disease management plans using results from our GEP test.”

About Melanoma
Cutaneous melanoma is diagnosed in approximately 76,000 people in the U.S. each year, according to the American Cancer Society. Seventy-five percent are diagnosed as Stage I or II, meaning there is no evidence of the melanoma spreading beyond the primary tumor. It is not the most prevalent form of skin cancer, but it is the most aggressive. Unlike other more common skin malignancies such as basal cell and squamous cell carcinomas, melanoma often spreads to other parts of the body, either via the lymphatic or blood system, resulting in cancers of distant organs including the brain or lungs. So, while it represents just 4% of skin cancers, melanoma accounts for about 80% of skin cancer-related deaths.

About Castle Biosciences
Castle Biosciences is a molecular diagnostics company dedicated to helping patients and their physicians make the best possible decisions about their treatment and follow-up care based on the individual molecular signature of their tumor. The Company currently offers tests for patients with uveal melanoma (DecisionDx®-UM; www.MyUvealMelanoma.com) and cutaneous melanoma (DecisionDx®-Melanoma; www.SkinMelanoma.com), with development programs in other underserved cancers. Castle Biosciences is based in Friendswood, TX (Houston), and has laboratory operations in Phoenix, AZ. More information can be found at www.castlebiosciences.com.

DecisionDx-UM and DecisionDx-Melanoma are the trademarks of Castle Biosciences, Inc. Any other trademarks are the property of their respective owners.